1. Field of the Invention
The present invention relates to a radio communications system and a method for radio communications to implement radio communications processing between communication terminal devices using a press-talk switch, and in particular, to a radio communications system and a method for radio communications that employs so-called CUG (Closed User Group) in which radio communications processing are implemented only within a group consisting of a specified number of people. The press-talk switch is a communication method enabling a radio communications process with a communication counterpart by pushing down a predetermined operation button that is provided in a radio communication terminal device.
2. Description of the Related Art
A great number of services are implemented using radio communications. One of such services using radio communications is a wireless communications system that is constructed with PTT (Push To Talk).
For example, there is an iDEN® system utilizing an integrated digital wide area networks developed by Motorola Inc., as is described in MOTOROLA, “iDEN Technical Overview,” [online], Aug. 8, 2000, Motorola Inc. Network Solution Sector [Sep. 12, 2003], the Internet. Download the Complete iDEN System Overview pdf (2.7Mb) (Chapter4: Dispatch Call Processing, 4-3: Dispatch Location Area, FIGS. 4-3 Simplified Dispatch Diagram). enhanced base transceiver device (EBTS) to implement half-duplex information communication using PTT (Push To Talk) between specific communication terminal devices grouped in advance, and transfers the audio information between user stations within a communication system. The PTT (Push To Talk) is a communication method with which a wireless communications with a communication counterpart is enabled by pushing down a specified operation button provided in a communication terminal device, and which is applicable to half-duplex transmission scheme.
In conventional radio communications systems with PTT, as shown in FIG. 1, a carrier that provides a radio communications system exclusively owns a PTT server (100) for establishing the radio communications processing among PTT communication terminal devices (1 to N), and a CUG server (200) for controlling the group information of communication terminal devices to perform radio communication among particular communication terminal devices (1 to N) with the PTT server (100) and the CUG server (200) connected to each other. A user can perform radio communication among particular PTT communication terminal devices (1 to N), only after a user of radio communication registers group information of PTT communication terminal devices (1 to N) in the CUG server (200) owned by the carrier providing a radio communications system using PTT, and pays the registration fee of radio communication in the group information to the carrier. This imposes limitation on the usage variations of radio communications and the price system of radio communications for users, and hence inhibits more users from using such a system.
In addition, as the market size base of various communications services are rapidly increasing, and a company such as ASPs (Application Service Provider), etc. needs to establish its own communication service to differentiate it from other companies' one and acquire more users. In fact, there exists in the market, potential users who would like around-the-clock use if they do not have to bear so much communications costs. A communication service for acquiring such users should be established.
The present invention is achieved to solve the above problems, and it is an object of the present invention to provide a radio communications system and a radio communications method that eliminate the limitation on the usage form of radio communications using a press-talk switch and enable users to easily perform radio communications processing.